The primary goal of the proposed research is to determine the mechanism of excretion of L-Asparaginase by S. cerevisiae. To accomplish this the following areas will be investigated: 1. The external form of L-asparaginase will be isolated and characterized. 2. The molecular properties of the external and internal forms of this enzyme will be compared. 3. The localization of the external and internal enzymes will be studied. 4. Mutants with an altered ability to excrete L-asparaginase will be isolated. 5. The properties of the enzyme from wild type and excretory mutants will be compared. 6. The mechanism of repression of L-asparaginase synthesis will be studied.